Apparatus for powered seat track adjustment or position setting of automotive seats are extremely well-known in the art. In most such track mechanisms, a unitary seat pan or seat cushion frame is mounted on the upper seat track for fore and aft movement under the control of a horizontal drive and for vertical movement of the forward and rear ends of the seat by operation of respective drives one for each seat end. The unitary seat pan includes the seat frame and seat cushion and back frame and back cushion. Thus, any movement of the seat frame and cushion causes like movement of both the back frame and back cushion, and any looseness in construction leads to a "chucking" condition prevalent in such mechanisms.
In U.S. Pat. No. 2,924,265 issued Feb. 9, 1960, the seat back is separated from the seat frame to prevent vertical movement of the seat back, while the seat frame and back are coupled together for horizontal motion. In this apparatus a single motor is used with solenoids actuatable to clutch the selected drive to the motor to drive the seat frame and seat back in a fore and aft direction and to drive the seat frame front and rear ends in a vertical direction. No additional seat back movement is disclosed by this reference.